Animal Health

Shining a spotlight on facial eczema

By Gemma Chuck

FACIAL ECZEMA (FE) can significantly affect dairy cattle productivity, health and welfare through animal deaths, reduced weight gain, reduced milk yield and reproductive performance.

While FE is mainly seen in east Gippsland, it has also been reported in other regions of Victoria.

Unconfirmed cases have also been reported in areas of coastal NSW, western and northern Victoria, South Australia and Tasmania.

The prevalence of FE may increase in the future as climate change could provide suitable conditions for outbreaks to occur.

What causes FE?

FE is caused by ingestion of spores of the fungus Pithomyces chartarum. These spores release a mycotoxin called sporidesmin which causes damage to the liver, bladder and mammary gland.

When does FE occur?

The fungus grows on most pasture plants, but has a preference for perennial rye-grass. It favours dead pasture litter at the base of plants and animals grazing short pasture at high stocking rates are at greatest risk.

Freshly produced spores are the most toxic but can lose their toxicity within one to two weeks if fungal growth stops after a change in the weather.

Outbreaks can occur in warm, humid weather with light rain (or irrigation) which is suitable for spore production.

Autumn is a high-risk period after a long, dry summer as pasture will be light and soil temperatures will still be warm enough for rapid pasture growth.

Signs of FE

Photosensitisation resembling ‘sunburn’ is a common sign frequently affecting the non-pigmented areas of skin. This occurs about two weeks after exposure to sporidesmin.

The skin of the face, ears, teats, and vulva, are often affected becoming reddened, then crusty and dark.

Eventually the skin peels off leaving large raw areas susceptible to infections and flystrike.

Cows may be restless, seek shade and lick or rub affected areas. If exposure is sudden, they may collapse in extreme pain.

However, in most outbreaks the majority of animals show little or no visible skin lesions, but have suffered liver damage.

For every cow in a herd with skin lesions, up to 10 or more cows may be affected sub-clinically. It is the 80 per cent of cows without skin lesions, but with liver damage, that contribute to the major economic losses.

Deaths, reduced weight gain and poor reproductive performance contribute to economic losses.

The udder and teats of lactating cows are often severely affected accompanied by a rapid drop in milk production. This may be temporary but in severe cases affected cows may dry off completely.

Treatment, prevention and control

There is no specific treatment for FE, and any treatment is considered to be symptomatic.

Affected animals should be housed during daylight and allowed to graze at night. At the very least they must be given access to shelter to help prevent further skin lesions and allow existing lesions to heal while the liver regenerates.

Areas where skin is peeling should be dressed with sun-blocking ointments. Contact your veterinarian if you suspect FE to discuss supportive treatment.

During high-risk periods or an outbreak, the following can help to minimise the risk of FE:

  • Avoid very close grazing: shift stock to the longest available pasture.
  • Avoid paddocks cut for hay or late-topped as there is a higher risk of toxicity. If unavoidable, ensure topped material is removed to reduce pasture litter.
  • Feed hay or other supplements to preserve ground feed and minimise close grazing of pasture.
  • Summer-growing crops are generally safer than pastures, so increase access to these when they are available.
  • If pasture is short and grazing pressure is heavy, farm irrigation may be valuable if available and used immediately.
  • Alternate grazing between native and improved pastures if feasible.
  • Pasture spore counts can be proactively monitored, allowing early intervention.

Oral zinc can be used to reduce the impact of FE but must be administered prior to exposure to sporidesmin.

Zinc does not have a therapeutic effect once cows are already showing signs of FE as it cannot reverse existing liver damage.

Daily drenching, in-feed and drinking water have been used to administer zinc.

There are potential side effects with prolonged zinc dosing and these should be discussed with your veterinarian.

Reference: “A Review of Facial Eczema”, Dairy Australia 2013.

■ Dr Gemma Chuck is a veterinary consultant for Apiam Animal Health, where she designs and delivers technical training programs for dairy farmers and veterinarians.